3. Body hair is muscular... kind of

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Don't try flexing it, as you’ll fail miserably, but your body hair does indeed have muscle cells. These smooth (not under your conscious control) arrector pili muscles cells hide behind body hair and like to flex (well, contract, actually) under specific conditions, such as when you're suddenly exposed to cold temperatures or you think you just saw a ghost. The consequence is that your hairs stand on end.